1. Field of the Invention
The invention relates to overhead rail-type material handling systems and more particularly to a single-bolt roof suspension for systems useful in mines.
2. Prior Art
One approach to suspending an overhead rail-type material handling system or apparatus is shown in U.S. Pat. No. 4,116,134 to Paul H. Troth entitled, "Hangers for Overhead Suspended Track." That system provides a support that permits some misalignment and is useful where overhead clearance is extremely limited. However, the mounting arrangement requires two roof bolts and the associated problem of locating and drilling the two holes for each suspension point to properly locate the support along a mine roof. Thus, notwithstanding the flexibility and the low head room achieved in that suspension, the two roof bolt requirement could be viewed as disadvantageous from a coal miner's point of view. In practice, the need to drill the sets of two holes, typically on six inch centers, in a mine roof on an axis perpendicular to a center line established for the monorail support, can prove difficult. Moreover, the pairs of holes have to be individually drilled because dual head roof drilling machines cannot drill on such close centers.
Single roof bolts, expandable into drilled holes, are disclosed by U.S. Pat. No. 3,219,199 issued to G. Lagerstrom, to support overhead rails in a mine tunnel.
Other overhead supports are shown by patents referenced in the aforementioned U.S. Pat. Nos. 4,116,134 and 3,219,199.